The present invention relates a semiconductor device and is suitable for use in a semiconductor device, for example, including a circuit for power compensation.
There has been known an apparatus including a drive system block with high power supply noise and a high operating current, and a control system block vulnerable to power supply noise and with a low operating current, which is designed to control the drive system block by the control system block. In this apparatus, when the drive system block and the control system block share a main power supply, separate power supply lines from the main power supply are used in order to reduce the power supply noise. Such an apparatus has a problem that if the power supply line that supplies power to the control system block is disconnected, the drive system block is out of control and headed for crash. To solve this problem, when the power supply line to the control system block is disconnected, power is supplied from the power supply line of the drive system block to the control system block as an emergency measure.
As a related art, Japanese Unexamined Patent Publication No. 2008-29160 discloses a backup power supply device. The backup power supply device is configured such that a main power supply including a first backflow prevention part and a backup power supply including a second backflow prevention part both supply power to the load by a power supply line common to the first and second power supplies. In this backup power supply device, a voltage regulator is provided in the first backflow prevention part to control the voltage of the main power supply so that the voltage between the terminals of the second backflow prevention part is zero.
Japanese Unexamined Patent Publication No. Hei 11 (1999)-252825 discloses a vehicle power supply system. This vehicle power supply system includes on-vehicle equipment coupled to a backup power supply line coupled to a battery of a car, as well as an auxiliary battery coupled to the backup power supply line to compensate for voltage drop in the backup power supply. A monitor for monitoring the voltage of the auxiliary battery or monitoring the voltage of the battery may be coupled to the vehicle power supply system.
Japanese Patent No. 4618617 discloses a power supply route failure diagnosis device of an external power supply controller. This power supply route failure diagnosis device is the power supply route failure diagnosis device of an external power supply controller that receives power supply from the external DC power supply. The power supply route failure diagnosis device includes a power supply part, a load drive circuit, a commutation path, a voltage detection part, a communication part, and a control part. The power supply part is coupled between the positive electrode terminal and negative electrode terminal of the external DC power supply by a first power supply route to receive power supply. A load drive circuit is serially coupled to an external load so that the external load is on the side of the positive electrode terminal between the positive and negative electrode terminals of the external DC power supply by a second power supply route. The load drive circuit switches between operation and non-operation of the external load by opening and closing the second power supply route. The commutation path includes a backflow prevention element coupled between the second power supply route between the external load and the load drive circuit and the first power supply route of the power supply part. When the voltage of the second power supply route is higher than the voltage of the first power supply route, the backflow prevention element of the commutation path commutates the power supply from the second power supply route to the first power supply route. The voltage detection part detects the power supply voltage in the power supply part. The communication part receives the power supply voltage value detected by the other controller with the same configuration and specifications to receive power supply from the external DC power supply. The control part is coupled to the load drive circuit, the voltage detection part, and the communication part. The control part includes a failure diagnosis part. When the difference between the power supply voltage value detected by the voltage detection part and the power supply voltage value in the other controller from the communication part is a predetermined value or more, the failure diagnosis part of the control part determines that a failure occurs in the first power supply route.